From ceba324bef9641d61239ed68a2f6671f59fa2831 Mon Sep 17 00:00:00 2001
From: Stjepan Glavina <stjepang@gmail.com>
Date: Mon, 16 Dec 2019 15:53:31 +0100
Subject: [PATCH] Fix feature flags

---
 src/lib.rs            |   3 +-
 src/task/yield_now.rs |   6 +-
 src/utils.rs          | 144 +++++++++++++++++++++---------------------
 3 files changed, 78 insertions(+), 75 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index 070df885..40ba15ab 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -246,14 +246,13 @@ cfg_std! {
     pub mod stream;
     pub mod sync;
     pub mod task;
-
-    pub(crate) mod rt;
 }
 
 cfg_default! {
     pub mod fs;
     pub mod path;
     pub mod net;
+    pub(crate) mod rt;
 }
 
 cfg_unstable! {
diff --git a/src/task/yield_now.rs b/src/task/yield_now.rs
index c7ddb175..bdb08eb6 100644
--- a/src/task/yield_now.rs
+++ b/src/task/yield_now.rs
@@ -1,7 +1,6 @@
 use std::future::Future;
 use std::pin::Pin;
 
-use crate::rt::RUNTIME;
 use crate::task::{Context, Poll};
 
 /// Cooperatively gives up a timeslice to the task scheduler.
@@ -44,7 +43,10 @@ impl Future for YieldNow {
         if !self.0 {
             self.0 = true;
             cx.waker().wake_by_ref();
-            RUNTIME.yield_now();
+
+            #[cfg(feature = "default")]
+            crate::rt::RUNTIME.yield_now();
+
             Poll::Pending
         } else {
             Poll::Ready(())
diff --git a/src/utils.rs b/src/utils.rs
index 79c2fdf5..c8984ba8 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -1,9 +1,3 @@
-use std::cell::UnsafeCell;
-use std::ops::{Deref, DerefMut};
-use std::sync::atomic::{AtomicBool, Ordering};
-
-use crossbeam_utils::Backoff;
-
 /// Calls a function and aborts if it panics.
 ///
 /// This is useful in unsafe code where we can't recover from panics.
@@ -58,71 +52,6 @@ pub fn random(n: u32) -> u32 {
     })
 }
 
-/// A simple spinlock.
-pub struct Spinlock<T> {
-    flag: AtomicBool,
-    value: UnsafeCell<T>,
-}
-
-unsafe impl<T: Send> Send for Spinlock<T> {}
-unsafe impl<T: Send> Sync for Spinlock<T> {}
-
-impl<T> Spinlock<T> {
-    /// Returns a new spinlock initialized with `value`.
-    pub const fn new(value: T) -> Spinlock<T> {
-        Spinlock {
-            flag: AtomicBool::new(false),
-            value: UnsafeCell::new(value),
-        }
-    }
-
-    /// Locks the spinlock.
-    pub fn lock(&self) -> SpinlockGuard<'_, T> {
-        let backoff = Backoff::new();
-        while self.flag.swap(true, Ordering::Acquire) {
-            backoff.snooze();
-        }
-        SpinlockGuard { parent: self }
-    }
-
-    /// Attempts to lock the spinlock.
-    pub fn try_lock(&self) -> Option<SpinlockGuard<'_, T>> {
-        if self.flag.swap(true, Ordering::Acquire) {
-            None
-        } else {
-            Some(SpinlockGuard { parent: self })
-        }
-    }
-}
-
-/// A guard holding a spinlock locked.
-pub struct SpinlockGuard<'a, T> {
-    parent: &'a Spinlock<T>,
-}
-
-unsafe impl<T: Send> Send for SpinlockGuard<'_, T> {}
-unsafe impl<T: Sync> Sync for SpinlockGuard<'_, T> {}
-
-impl<'a, T> Drop for SpinlockGuard<'a, T> {
-    fn drop(&mut self) {
-        self.parent.flag.store(false, Ordering::Release);
-    }
-}
-
-impl<'a, T> Deref for SpinlockGuard<'a, T> {
-    type Target = T;
-
-    fn deref(&self) -> &T {
-        unsafe { &*self.parent.value.get() }
-    }
-}
-
-impl<'a, T> DerefMut for SpinlockGuard<'a, T> {
-    fn deref_mut(&mut self) -> &mut T {
-        unsafe { &mut *self.parent.value.get() }
-    }
-}
-
 /// Add additional context to errors
 pub(crate) trait Context {
     fn context(self, message: impl Fn() -> String) -> Self;
@@ -338,3 +267,76 @@ macro_rules! extension_trait {
         extension_trait!($($tail)*);
     };
 }
+
+cfg_default! {
+    use std::cell::UnsafeCell;
+    use std::ops::{Deref, DerefMut};
+    use std::sync::atomic::{AtomicBool, Ordering};
+
+    use crossbeam_utils::Backoff;
+
+    /// A simple spinlock.
+    pub struct Spinlock<T> {
+        flag: AtomicBool,
+        value: UnsafeCell<T>,
+    }
+
+    unsafe impl<T: Send> Send for Spinlock<T> {}
+    unsafe impl<T: Send> Sync for Spinlock<T> {}
+
+    impl<T> Spinlock<T> {
+        /// Returns a new spinlock initialized with `value`.
+        pub const fn new(value: T) -> Spinlock<T> {
+            Spinlock {
+                flag: AtomicBool::new(false),
+                value: UnsafeCell::new(value),
+            }
+        }
+
+        /// Locks the spinlock.
+        pub fn lock(&self) -> SpinlockGuard<'_, T> {
+            let backoff = Backoff::new();
+            while self.flag.swap(true, Ordering::Acquire) {
+                backoff.snooze();
+            }
+            SpinlockGuard { parent: self }
+        }
+
+        /// Attempts to lock the spinlock.
+        pub fn try_lock(&self) -> Option<SpinlockGuard<'_, T>> {
+            if self.flag.swap(true, Ordering::Acquire) {
+                None
+            } else {
+                Some(SpinlockGuard { parent: self })
+            }
+        }
+    }
+
+    /// A guard holding a spinlock locked.
+    pub struct SpinlockGuard<'a, T> {
+        parent: &'a Spinlock<T>,
+    }
+
+    unsafe impl<T: Send> Send for SpinlockGuard<'_, T> {}
+    unsafe impl<T: Sync> Sync for SpinlockGuard<'_, T> {}
+
+    impl<'a, T> Drop for SpinlockGuard<'a, T> {
+        fn drop(&mut self) {
+            self.parent.flag.store(false, Ordering::Release);
+        }
+    }
+
+    impl<'a, T> Deref for SpinlockGuard<'a, T> {
+        type Target = T;
+
+        fn deref(&self) -> &T {
+            unsafe { &*self.parent.value.get() }
+        }
+    }
+
+    impl<'a, T> DerefMut for SpinlockGuard<'a, T> {
+        fn deref_mut(&mut self) -> &mut T {
+            unsafe { &mut *self.parent.value.get() }
+        }
+    }
+}